Devices for ultrahigh-density, high-speed data storage applications using thermomechanical writing and thermal readout in thin polymer film as storage media work on bases of atomic force microscopy (AFM) technique and are described in the following publications representing the state of the art:                H. J. Mamin et al., “High density data storage using proximal probe techniques”, IRM J. Res. Develop., Vol. 39, No. 6, pp. 681700, 1995.        E. Grochowski and R. F. Hoyt, “Future Trends in Hard Disk Drives”, IEEE Trans. Magnetics Vol. 32, No. 3, pp. 18501854, 1996        R. P. Ried et al., “6 MHz 2N/m Piezoresistive AtomicForceMicroscope Cantilevers with Incisive Tips”, J. Microelectromech. Syst., Vol. 6, No. 4, pp. 294302, 1997,        U.S. Pat. No. 5,835,477 entitled MassStorage and        P. Vettiger et al., “Ultrahigh Density, High data rate Micromechanical Scanning Probe Storage System”, Proc. Intl. Conf. on Micro and NanoEngineering 98, LeuvenBelgium, September 1998, to be published in Microelectronic Engineering.        
A basic arrangement for thermomechanical writing and readout is shown in FIGS. 1a-1c, representing prior art. Very close to the surface of a storage media 1, consisting of a polymer film, a tip 2 is positioned directing towards the surface of the storage media 1. The tip 2 protrudes from the loose end of a cantilever 3 which is fixed to a plane shaped carrier element 4 which is positioned in a defined distance from the surface of the storage media. For writing binary information into the storage media 1, the polymer surface is locally softened or melted with the heated tip 2 by simultaneously applying a light pressure onto the tip 2 by the cantilever 3, resulting in nanometer-scale indentations in the surface of the storage media 1 representing the binary information in the form of indents.
Heating of the tip 2 is provided by a resistive platform underneath the tip. For reading the binary information stored in the storage media 1, the heated platform and the heated tip are also used as a sensing element to detect topographical changes on the surface of the polymer film. While reading, a low constant electrical power is applied to heater platform so that the temperature of the platform is modulated by the distance between the platform and the storage media. The temperature change is measured through the resistivity of the platform and depends on the heat sinking capability of the heater platform environment. By scanning bit indentations, as shown in FIG. 1b, the distance between the platform and the surface of the storage media can change by some 10 nm, resulting in a platform temperature change due to cooling of the storage media. In FIG. 1b, the tip of the cantilever dips into the indentation causing more cooling of the cantilever system than that shown in FIG. 1c where the cantilever has a greater distance towards the surface of storage media.
For designing the cantilever with a tip at its loose end, some important aspects have to be considered. The mass of the cantilever has to be as small as possible to obtain soft, high-resonant frequency cantilevers. Soft levers are required for low loading force in order to eliminate or reduce tip and media wear, whereas a high resonant frequency allows high speed scanning. Also, the tip height should be as short as possible, as heater platform sensitivity depends strongly on the platform-media distance, as described relating to FIG. 1. However this requirement contradicts the demand of a large gap between the surface of the carrier element and the storage media to guarantee that only the tips are making contact with the media and not with the carrier element.
The object of the present invention is to realize a device especially for thermomechanical writing and thermal readout of binary information in a storage media, taking the above mentioned demands into account. Especially, the object of the present invention is to provide a tip arrangement which allows an array configuration of a multitude of single cantilevers and to guarantee as well that each single tip of said cantilevers stays in close contact to the surface of the storage media without wearing the surface of the storage media. Of course devices comprising the same basic assembly, i.e. having a cantilever connected to an almost plane carrier element staying apart from a surface, said cantilever having a tip at its loose end being in close contact to said surface, but usable for different applications like lithography, surface modification and/or imaging, just to name a few, shall also be improved in the same way and with the same inventive steps as in the case of the before mentioned device.
It is a further object of the present invention to improve the tip geometry and the method of production the cantilever and tip at the loose end of the cantilever, using methods which are easy to handle allowing a low-cost fabrication and high yields. The tip volume shall be as small as possible so that the tip mass can be reduced for realizing a high-resonant frequency cantilever system and reduce the heating time constant.